Blood tests for obesity
A blood test in the context of obesity looks at metabolic health, liver and kidney function, the thyroid and possible nutritional deficiencies. Weight alone does not show how these parameters are, and a blood test does not explain the cause of obesity on its own either.
At Análisis Médicos we have designed profiles for three moments: an assessment before starting treatment with GLP-1 agonists, a check during treatment, and a broader metabolic assessment of obesity. GLP-1 treatments are one part of the category, not its only reason for existing.
Blood tests for obesity available
If you are not sure which one suits you, there is a guide below the list to help you choose.
- Análisis MédicosBlood test before starting GLP-1Dr. Antonio Mas€129.00
Blood test before starting GLP-1
Blood test before starting treatment with GLP-1 or similar medicines, such as Ozempic or Wegovy (semaglutide), Mounjaro (tirzepatide) or Saxenda (liraglutide). It includes glucose, glycated haemoglobin, insulin, cholesterol, kidney, liver, full blood count, TSH and a selection of vitamins and minerals. It provides reference values before the first dose and identifies abnormalities that call for medical context.
- First line
- Análisis MédicosGLP-1 monitoring blood testDr. Antonio Mas€119.00
GLP-1 monitoring blood test
Monitoring blood test during treatment with Ozempic, Wegovy, Mounjaro, Saxenda or another GLP-1 or similar medicine. It includes glucose, glycated haemoglobin, cholesterol, kidney and liver function, electrolytes, full blood count, ferritin, vitamin D, vitamin B12, folic acid, uric acid, calcium and magnesium. It allows metabolic progress to be compared and relevant changes to be monitored during weight loss.
- For follow-up
- Análisis MédicosMetabolic blood test for obesityDr. Antonio Mas€199.00
Metabolic blood test for obesity
Metabolic blood test for obesity with glucose, glycated haemoglobin, insulin, the HOMA-IR index, cholesterol, ApoB, ApoA-I, lipoprotein(a), high-sensitivity CRP, liver function with FIB-4, kidney function and a selection of vitamins and minerals. It assesses the metabolic, cardiovascular, liver and nutritional context beyond weight.
How it works
You can order any of our blood tests for obesity without your doctor having to request it:
- Price
- From €119.00
- Prescription
- Not needed
- Appointment
- Not needed
- Results
- 1 to 5 working days
- Your test request, in minutes. Order the profile you want and it arrives in your inbox straight away, with the preparation instructions.
- Wherever suits you, with no appointment. You can have your test at any of the 45 partner centres, and the laboratory emails you the results within a few days.
- With an invoice. When you order, you receive an invoice you can submit if you have reimbursement health insurance. How it works, step by step.
How to choose your blood test for obesity
This is not medical advice and does not replace a consultation: it is the reasoning I would use to choose, in case it helps you decide which one to order.
Before starting treatment with GLP-1 agonists, the baseline profile brings together the data worth knowing before you begin. It does not decide whether the medicine is indicated or which one should be used.
During a treatment that has already been prescribed, the monitoring profile reviews the parameters that can change with weight loss or that are worth watching during follow-up. How often it is repeated depends on progress and on the clinical plan.
For a broader metabolic assessment of obesity, the metabolic blood test extends the assessment of glucose, lipids, liver, kidney, thyroid and inflammation. It is not tied to a specific medicine.
Dr. Antonio Mas
What is assessed besides weight
Glucose, glycated haemoglobin and insulin give information about carbohydrate metabolism. Cholesterol and triglycerides are part of cardiovascular risk. Liver enzymes, kidney function and TSH help complete a general health assessment.
Some profiles also include a full blood count, iron, vitamin B12, folic acid or vitamin D. These tests can be useful when food intake has changed, when there is a history of deficiency or when clinical follow-up justifies them.
Why the baseline and monitoring profiles are different
Before starting treatment, it is useful to have a baseline reference and to identify problems that should be assessed. During follow-up the question changes: progress is compared and selected parameters are monitored.
This does not mean that nutritional stores inevitably run down when you lose weight, or that everything has to be repeated at a fixed interval. The need depends on diet, symptoms, the speed of weight loss, medication and medical history.
What a blood test does not decide
It does not choose the medicine, set the dose or, on its own, explain a lack of response or a weight plateau. Nor does it replace medical follow-up of side effects. It serves to add objective data to that process.
Before your blood test
The profiles in this category require 8 to 12 hours of fasting. You can drink water.
If you already use a GLP-1 agonist, keep to your usual schedule unless whoever manages your treatment tells you otherwise. Also mention any other medicines and supplements you take.
Do not stop iron, vitamin B12 or other supplements because of a general rule. Follow the specific preparation on the profile page and the instructions of whoever prescribed them.
Frequently asked questions
- Should I have a blood test before starting GLP-1 treatment?
- A baseline assessment can provide useful information before starting, but whether the treatment is indicated and which tests are required should be decided by the professional who prescribes it.
- How often should the blood test be repeated during treatment?
- There is no single interval. It depends on the starting situation, progress, symptoms and the follow-up plan.
- Do I have to stop GLP-1 treatment to have the blood test?
- Not as a general rule. Keep to the prescribed schedule unless whoever manages your treatment gives you a different instruction.
- Can a blood test explain why I am not losing weight?
- Not on its own. It can identify or monitor specific factors, but a weight plateau requires assessing diet, activity, medication, tolerance and progress.
- Is the broadest profile always the most suitable?
- No. The baseline, monitoring and broad metabolic profiles answer different questions. The choice depends on the moment and the goal.
If you already have your results
A figure only makes sense in its context. Medical history, symptoms, medication and the conditions of the sample can change what it means. Results are assessed in a consultation; this page is for comparing and ordering profiles.
The laboratory sends you the results directly. You can then review them with the professional of your choice.
Guide reviewed by Dr. Antonio Mas, specialist in Endocrinology and Nutrition, Spanish medical licence no. 080846289, in September 2026.
And if you were looking for something else, here are all the blood tests in the catalogue, grouped by topic.